This game is pretty neat; I'd love to see some further development.
I was thrown at first because (at least the first time I launched the game in browser), my starting characters couldn't interact with anything (gems, mates, even spikes, etc.), and so they'd all just die of old age. After a relaunching the issue seemed to be resolved.
While it's a style choice, I think it would be kind of nice to implement HP rather than sudden death upon encountering something dangerous. You already even have the necessary mechanic: just dock a few years from the critter's remaining lifespan. That way the player can learn to stay out of water, etc., without as much an interruption to play.
Also, pressing 'x' once for suicide is pretty easy to hit on accident. It would be nice if there was a confirmation.